An occupation ceiling is a limit on the number of invitations that can be issued through SkillSelect each year.
An occupation ceiling is applied to:
Skilled independent visas
Skilled regional sponsored visas
Skilled or business state or territory sponsored visas.
You will not be invited to apply for one of these visas if your occupation has reached its ceiling.
You can see the occupation ceilings here: https://www.border.gov.au/Trav/Work/Skil